Circuit interrupter



March 9, 1943. WALL CE 2,313,185

CIRCUIT INTERRUPTER Filed Sept. 9, 1939 WITNESSES: INVENTOR finfa f M//4:e

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Patented Mar. 9, 1943 CIRCUIT INTERRUPTER James M. Wallace, North Braddock, Pa., assignor to Westinghouse Electric a Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application September 9, 1939, Serial No. 294,012

1': Claims. (or. 200-114) My invention relates generally to circuit interrupting devices capable of automatically interrupting currents of a predetermined magnitude, and particularly to interrupters of this type which are constructed to automatically drop out, or remove themselves from the circuit after an interrupting operation. I will disclose my invention in connection with high-voltage fuses, which are commonly used for high voltage circuit protection against heavy overloads or short circuits.

It is an object of my invention to provide an interrupting device which, upon operation thereof to interrupt a circuit, will automatically disengage itself from the circuit to insert an air ga in the circuit.

. It is a further object of my invention to provide a high-voltage fuse with novel supporting means which will collapse upon blowing of the fuse to permit the fuse to move out of its associated circuit.

It is a further object of my invention to. provide a high-voltage fuse of the type embodying a replaceable fuse structure with novel supporting means for the fuse and replaceable fuse structure.

A still further object of my invention is to provide a supporting means for a high-voltage fuse permitting novelclosing and opening movements of the fuse.

Another object of my invention is to provide a high-voltage fuse having novel means incorporated in the fuse to enable the fuse to automatically remove itself from a circuit after it has blown and the resulting arc extinguished.

These and other objects of my invention will become more apparent upon consideration of the following specification and the attached drawing, in which:

Figure 1 is a side view, partly in section, of a fuse embodying my invention;

Fig. 2 is an enlarged plan view of the supporting ring used in the fuse shown in Fig. 1;

Fig. 3 is across-sectional view taken on the line III-III of Fig. 2;

Fig. 4 is a reduced side view of the fuse shown in-Fig. I mounted in a circuit between a pair of contact members; and

Fig. 5 is a front view of the device shown in Fig. 4-.

In general, my'invention consists of a standard type of fuse having novel lower pivotal supporting means; which supporting means is slidably mounted on the fuse tube, but normally restrained against movement by the fusible element, so that upon blowing of the fuse the supporting means is free to slide longitudinally of the fuse tube. The fuse has its lower pivotal supporting means pivotally mounted on one contact member, and its upper end is received in an indentation inthe lower side of a resilient contact member which is stressed to continually exert a force to maintain the fuse seated on the lower contact. when the fuse blows, the pivotal support on the fuse being movable relative to the fuse, allows the entire fuse to slide longitudinally downwardly away from the upper contact by gravity, and since the fuse is mounted in a position inclined to the vertical, the fuse may then pivot about its lower support to a. depending vertical position, thus removing it from the circuit.

The fuse shown in Fig. 1 isin general the same as that disclosed in the patent to H. L. Rawlins, No. 1,976,634, and includes an inner elongated tube 2 of insulating material, such, for example, as fibre or the like, having threaded ends to threadedly receive, respectively, an upper terminal cap 4, and a lower terminal sleeve 6. The upper terminal cap has an outwardly and downwardly projeoting flange to. provide a channel 8 for receiving the end of an outer protective sleeve l2 of a weather-proof insulating material, such as porcelain, glass, or the like. Packing material 10 is provided between the insulator cap 4 and the outer weather-proof tube i2. The lower end of the outer weather-proof tube I2 abuts against the upper end of the lower terminal sleeve 6 with packing material ll interposed therebetween. A refill element It is provided in the lower portion of the insulating tubes, and includes an outer insulating tube 18 of fibre or the like, having a lining 20 of a material capable of emitting an arc extinguishing gas when placed in proximity to an electric arc. This material is preferably boric acid, or the like. In the bore through the boric acidlining, there is provided an elongated arc drawing rod 22. A fusible link 26 is secured to the lower end of the arc drawing rod 22 by any suitable means, such as by soldering, and is also secured to a terminal ferrule 24, threaded onto the lower end of the outer refill tube It, as by the screw 28. The upper end of the arc drawing rod 22 is secured to a piston member 30 slidably mounted in the inner fuse tube 2, A coil tension spring 32 is held under stress between the piston member 30 and the upper terminal cap 4. As shown, the spring 32 has its lower endthreadedly engaged with an extension of the piston member 30, and has its upper end threadedly engaging an upper spring support member 64 held to the upper terminal cap 4 by the cap nut 36. The spring 62 is maintained under tension, and its force is exerted from the cap nut 36 at one end thereof, to the piston member 86, at the other end thereof through the are drawing rod 22, fusible element 26 and the terminal ferrule 24, which is thus maintained in engagement with an inwardly extending projection 46 on the lower terminal sleeve 6. The lower end of rod 22 may be maintained in the position shown by the close fit of piston member 30 in tube 2 or by fusible element 26, or if desired the lower end thereof may be allowed to engage the side wall of the bore through arc extinguishing material 26.

The electrical circuit through the fuse extends from the upper terminal cap 4 through the cap nut 36, the spring support 34, a flexible shunt 36 made of any suitable conducting material, such as, for example, copper; the shunt 36 being connected at one end to the spring support 34 and at its other end to the piston member 30. The circuit through the fusecontinues from the piston member 30 through the are drawing rod 22, fusible element 26, terminal ferrule 24 to the lower terminal sleeve 6.

Slidably mounted on the lower terminal sleeve 6 is a supporting ring 42. As shown in Fig. 2, the supporting ring has oppositely disposed machine screws 46 extending inwardly through the sides of the ring in threaded engagement therewith and having parts projecting both inwardly and outwardly of the ring. The screws 46 are screwed down tightly to maintain them in the position shown, and are removable to facilitate ready assembly of the parts. The inner ends of the machine screws areadapted to be received in opposed slots 44 cut in opposite sides of the lower terminal sleeve 6 (see Fig. 4). A clamping ring 48 is provided around the lower end of the refill terminal ferrule 24, and includes outwardly extending ends secured together to clamp the ring to the ferrule, as by a bolt and nut assembly 50 extending through the outwardly extending ends of the clamping ring. The supporting ring 42 is provided with three tangential apertures equally spaced about the perimeter of the ring for receiving pivot pins 62 which are pressed in, or otherwise suitably secured in place. Mounted on each pivot pin is a locking dog 54 of substantially L-shape, with the short leg thereof pivotally mounted on a pivot pin 52, and the long leg thereof adapted to extend beneath and inwardly of the supporting ring, in the normal position of the fuse, as shown in Figs. 1 and 3. The position of the clamping ring 46 is shown in, dotted lines in Fig. 3.

In the normal condition of the fuse, it is apparent that the support ring 42 is locked in position at the lower end of slots 44 by engagement of the long legs of the locking dogs 64 thereon, between the outer end of the lower terminal sleeve 6 and the clamping member 46..

When the fuse blows, the connection between the are drawing rod 22 and the terminal ferrule 24 is destroyed. Spring 62 is then free to rapidly move the are drawing rod 22 upwardly, and draw out an arc in the bore provided in the boric acid lining which will emit a gas which will be rapidly expelled through the lower end of the fuse to extinguish the are formed. The reaction force of the escaping gas will tend to move the entire fuse upwardly. When the arc has been extinguished, flow of gas will cease and the fuse link 26 having separated, the renll I6 is then free to move downwardly out of the fuse tube. As soon as the clamping member 46 on the refill, moves far enough to permit pivoting of the dogs 64 outwardly, the entire fuse tube may then move relative to the supporting ring 42. The reiill is prevented from falling entirely out of the fuse tube by a flexible strap 14 connected by the screws 16 to. the lower fuse 1 terminal sleeve 6 and the clamping ring 46.

There is sufficient slack in this strap I4 to permit the refill to move downwardly far enough to release the dogs 64.

In Figs. 4 and 5, I have shown the fuse supported on a pair of insulating supports 66; the

lower insulating support 66 having an outwardly projecting terminal support 66 with an outer bifurcated end which includes the spaced hooked leg portions 66 for pivotally receiving the heads of the screws 46 provided on the supporting ring 42 of the fuse. The upper insulator is provided with a generally arcuate contact member 62 having an indentation 64 in its lower side for receiving the cap nut 66 on the upper end of the fuse. The upper contact 62 is preferably resilient so as to constantly exert a force on the upper end of the fuse to maintain the screws 46 on the fuse support ring, seated on the hooked arms 66 of the lower contact. The upper terminal cap 4 of the fuse is provided with upwardly and outwardly extending, spaced, integral supporting arms 46, for pivotally supporting therebetween, as at 67, an apertured hook-stick operable member 66, having a rearwardly extending projection HI adapted to engage the outer end 12 of the upper contact 62, when the operating member 66 is moved in a clockwise direction, thus providing for manual release or disconnection of the fuse from the upper contact 62, so that the fuse may thereafter be lifted out of the lower contact 66 when desired. When thefuse is to be inserted in engagement with. the contacts, it may be lifted so that the heads of screws 46 are received in the hooked portions 66 of the lower contact 66. The fuse can then be pivotally moved in a counter-clockwise direction into engagement with the camshaped outer end 12 of the upper contact to cam the outer end of the upper contact upwardly, and on continued movement of the fuse in the same direction, the cap nut 36 on the upper end of the fuse will snap into the depression 64 in the upper contact member.

Upon blowing of the fuse, it should now be apparent that rupture of the fusible element 26 will establish an are which is rapidly drawn out into engagement with the boric acid lining 26 to cause evolution of a large quantity of gas to flow through the arc and out the lower end of the fuse. The reaction force, due to the expulsion of gas from the lower end of the fuse, will maintain the fuse in engagement with the upper contact 62 until the arc is extinguished and the flow of gas ceases. The fuse refill I6 may then drop down, at least a sumcient distance to release the locking dogs 64 to allow them to pivot outwardly, and inasmuch as the fuse support ring 42 is held by the lower contact member against downward movement, the entire fuse may then move downwardly relative to the supporting ring 42 by the force of gravity. This latter movement is also initiated by the pressure exerted on the upper end 2; the fuse by the upper resilient contact member 15 As shown in Fig. 5, the fuse element initially contact 58 and a new refill blown refill IS in the manner described in the eating that the fuse is blown, and inserting an air gap in the circuit which is equal to the distance between the two contact members 58 and 62. From the blown position shown in dotted lines in Fig. 4, the fuse may be easily lifted from the lower aforementioned Rawlins patent, and the fuse reinserted in the circuit.

I have thus provided a fuse which is generally of a standard type, but which embodies novel pivotal supporting means therefor, which supporting means is movable relative to the fuse and is incorporated as part of the fuse itself, and which is normally maintained at one extremity of its movement by the fusible element, so that when the fuse blows, the resultingarc is drawn out and extinguished and then the fuse support is free to move relative to the fuse. As described in connection with Figs. 4 and 5, this release of the fuse supporting means permits movement of the fuse itself, longitudinally of the fuse and laterally away from an upper contact member, to disengage that contact member, and to then permit the fuse to pivot about its movable supporting means to increase the air gap in the circuit and to give a clear visual indication of the condition of the fuse.

Having specifically described a preferred embodiment of my invention in accordance with the patent statutes, I'wish it to be understood that I desire my invention to be given the broadest possible construction, and be not limited to the particular embodiment disclosed herein, since it will be obvious, particularly to persons skilled in the art, that many changes and modifications may be made in the particular embodiment disclosed without departing from the broad spirit and scope of my invention. 1, therefore, desire that my invention be given the broadest possible interpretation, and be limited only by what is expressly set forth in the appended claims.

I claim as my invention:

' 1. In a circuit interrupting device, means for automatically interrupting currents above a predetermined value having a terminal support slidably mounted thereon and maintained in a supporting position thereon by said. means, whereby upon an interrupting operation of said means, said support is released to permit relative movement of said means and'support, and said support including conducting trunnion portions adapted to pivotally support and electrically connect said device relative to a contact means.

2. In a. circuit interrupting device, an interrupter casing having a terminal ferrule adjacent one end thereof, means for automatically interrupting currents above a predetermined magnitude in said casing, a slidable support on said casing ferrule and maintained in a supporting position by said means, whereby upon operation of said means to interrupt the circuit, said support is released to permit relative movement of the support and casing.

substituted forl the casing having an open end, means for automati 'cally interrupting currents of a predetermined magnitude in said casing, a support for the casing slidably mounted thereon adjacent said open end, movable keeper elements on the support adapted to engage the open end of said casing, and means held in engagement with said keeper elements by said interrupting means to normally maintain the support in one supporting position relative to the casing, but releasing the support upon operation of said interrupting means to interrupt the circuit, to permit relative movement.

of the support and casing.

4. In a high-voltage fuse, a tubular casing, a fuse refill slidably mounted in the casing, a movable support on the casing, said refill including a fusible element for normally maintaining the refill in the casing, and said support in a normal supporting position relative to the casing, andmeans connecting said refill and casing for permitting limited relative movement thereof when said fusible element blows.

5. In a high-voltage fuse, a tubular casing, a fuse refill insertable in an open end of the casing, stop means limiting the insertion of said refill in said casing, said refill including a fusible element having a connection to said casing to normally maintain the refill in position in the casing, a support slidably mounted on said casing and adapted to be engaged by a part on said refill so as to be maintained in one supporting position relative to said casing by said refill, whereby .upon blowing of saidfusible element the refill and support may move relative .to said casing.

6. In a high-voltage fuse, a tubular casing, a

- casing, said refill including a fusible element 3. In a circuit interrupting device, a tubular having a connection to the casing to maintain the refill in position in the casing in engagement with said stop means, a support slidably mounted on the casing and maintained in one supporting position relative to said casing by said refill, whereby upon blowing of said fusible element the refill is released for movement outwardly relative to said open end of said casing, and means limiting movement of the refill relative to the casing, but allowing sufiicient relative movement to release said support for movement relative to said casing.

7. In a high-voltage fuse, a tubular casing having a terminal ferrule adjacent one end thereof, a fuse refill insertable in the open end of the casing and including afusible element having a connection to the casing to maintain the refill in position in the casing, a support mounted for limited sliding movement on said casing ferrule and maintained adjacent one extremity of its movement by'said refill, whereby upon blowing of said fusible element the refill and support may move relative to said casing.

8. In a high-voltage fuse, a tubular casing, a

fuse refill insertable in an open end of the casing,

stop means limiting the insertion of said refill in said casing, said refill including a fusible element.

- to normally maintain the support in one supporting position, but releasing the support to permit relative movement of the support and housing upon operation of said interrupting means to in terrupt the circuit.

10. In a circuit interrupting device, a tubular casing having an open end, means for automatically interrupting currents of a predetermined magnitude in said casing, a support for the easing slidably mounted thereon adjacent said open end, movable keeper elements on the support adapted to engage the open end of said casing,

and an annular retaining ring held in engagement with said keeper elements by said interrupting means to normally maintain the support in one supporting position relative to the casing, but releasing the support upon operation of said interrupting means to interrupt the circuit, to permit relative movement of the support and easing.

ll. In a fuse, a tubularcasing, fusible means in said casing and having one end thereof secured relative to said casing, a support for said casing slidably mounted thereon, movable keeper elements on said support and adapted to engage an end of said casing, retaining means adapted to be maintained in engagement with said keeper elements by said fusible means to normally maintain said support at a predetermined supporting position, and operable upon blowing of said fusible means to permit relative movement of said support and easing. v

12. In a fuse, a tubular casing having terminals adjacent opposite ends thereof, fusible means in said casing, a support for said casing slidably mounted thereon, movable keeper elements on said support and adapted to engage an abutment on said casing to maintain said support in a predetermined supporting position relative to said casing, retaining means for maintaining said keeper elements in engagement with said abutment, and said fusible means connected between said retaining means and one terminal of said casing, whereby to release said support for relative movement upon fusion thereof.

13. In a fuse, a tubular casing having terminals adjacent opposite ends thereof, fusible means in said casing, a support for said casing slidably mounted thereon, movable keeper elements on said support and adapted to engage an abutment on said casing to maintain said support in a predetermined supporting position relative to said casing, retaining means for maintaining said keeper elements in engagement with said abutment, and said fusible means connected between said retaining means and one terminal of said casing, whereby to release said support for relative movement upon fusion thereof, andfiexible conducting means connecting said retaining means and the other terminal of said casing.

14. In a circuit interrupting device, a tubular casing having an open end, means for automatically interrupting currents of a predetermined circuit interrupting operation.

15. In a high-voltage fuse, a tubular mm; of insulating material having terminals adjacent opposite ends thereof, said casing having an open end for the insertion of a refill unit, said mit to the other limit of its including an insulating tube having a laterally extending locking flange at one end thereof, oooperating stop means on said tube and casing for limiting inserting movement of said unit into said casing with said flange positioned adjacent the open end of said casing in a position to look a fuse support therebetween, fusible means in said refill tube and having one terminal thereof connected to said refill tube, means connecting the other terminal of said fusible means under tension to the terminal adjacent the other end of said casing to maintainsaid, operative position-in saidholder with said stop means in engagement and said flange adjacent to but spaced from the open end of said casing.

16. In a high-voltage fuse, a tubular casing of insulating material having terminals adjacent opposite ends thereof, said casing having an open end for the insertion of a refill unit, said unit including an insulating tube having a laterally extending locking flange at one end thereof, cooperating stop means on said tube and casing for limiting inserting movement of said unit into said casing with said'flange positioned adjacent the open end of said casing in a position to lock a fuse support therebetween, fusible means in said refill tube and having one terminal thereof connected to said refill tube, means connecting the other terminal of said fusible means under tension to the terminal adjacent the other end of said casing to maintain said refill in operative position in said holder with said stop means in engagement and said flange adjacent to but spaced from the open end of said casing, annular fuse supporting means adapted to be slidably mounted on said casing adjacent the open end thereof and having portions normally received in the space between said locking flange and open end of said casing for preventing relative sliding movement of said supporting means and casing. whereby upon fusion of said fusible means said refill is released for movement outwardly of said casing to thereby release said sup porting means for relative sliding movement on said casing.

17. In a high-voltage fuse, a tubular casing, a renewable fuse refill unit limitedly slidably mounted in the casing, said refill including a tubular insulating enclosure and a fusible element secured therein and connected to said casing for normally maintaining said refill unit in fixed relation to said casing at one limit of its movement relative to said casing, whereby said refill is released for movement relative to said casing movement when said fusible element blows.

JAMES M. WALLACE 

